Conventional millimeter-wave modules are cavity modules containing multiple monolithic microwave integrated circuits. A desire for smaller modules to reduce cost, maintain mechanical strength and to maximize gain pushes designers to place the chips closer together. However, the closer spacing increases an unwanted coupling and feedback between the chips that leads to gain ripple and, in some situations, oscillation. A standard solution is to construct metal walls between the chips. The metal walls increase a cost of the module.
It would be desirable to implement an electromagnetic wall in a millimeter-wave cavity.